This invention relates to activated carbon impregnated with an organic amine compound to improve the performance of the activated carbon against toxic perfluorocarbons, particularly trifluoronitrosomethane (TFNM), and to a process for impregnating activated carbon with organic amine compounds.
Activated carbon has been used in breathing gas filter canisters of gas masks for the removal of toxic gases both commercially and in military applications. For the removal of specific poisonous gases such as hydrogen cyanide (HCN) and cyanogen chloride (CNCl), activated carbons are used which typically contain certain metals (copper, chromium, and silver) usually in the form of an oxide crystallite. Typically, these adsorbents are known in the trade as ASC Whetlerite carbon or ASC/TEDA if the carbon also contains triethylenediamine, TEDA. The function of these metals or metal compounds is primarily to break down HCN or CNCl by chemical reaction(s) into innocuous gaseous products and/or products which are readily physisorbed or chemisorbed onto the activated carbon.
Trifluoronitrosomethane (TFNM), is a perfluorocarbon which is blue in colour and has a boiling point of -84.degree. C. Under sunlight (UV irradiation), this gas dimerizes, and loses its intense blue hue to become faintly yellow. TFNM is sufficiently toxic to be a high hazard, even to subjects protected by standard carbon adsorbent filters. The amine-impregnated activated carbon invention described herein was found to be particularly effective in chemisorption of this type of compound and is the first carbon adsorbent capable of removing this toxic gas from the breathing air stream.